Gas turbines are widely used in commercial operations for power generation. Generally, a gas turbine may include a plurality of combustors disposed in an annular array about the axis of the engine. A compressor supplies compressed air to each combustor, wherein the compressed air and fuel are mixed and burned. Hot gases of combustion flow from each combustor to the turbine section of the engine wherein energy is extracted from the combustion gases to produce work.
Controlling combustor performance is necessary to achieve and maintain satisfactory overall gas turbine operation and to achieve acceptable emission levels, such as NOx levels. It is generally known that increasing the amount of hydrogen present in the air/fuel mixture supplied to the combustors can significantly impact the operation of a gas turbine. For example, the presence of certain amounts of hydrogen within the air/fuel mixture can increase combustion stability and turndown, thereby enabling lower emissions and emissions compliant operation at a lower load.
Fuel reforming systems are known that reform or convert conventional hydrocarbon fuel sources into a hydrogen-rich gas stream. For example, reformers utilizing a partial oxidation reactor, such as a catalytic partial oxidation (CPOX) reactor, are known that partially oxidize an oxygen/fuel mixture to form primarily hydrogen and carbon monoxide. Such reforming systems have traditionally been directed towards the fuel cell market, particularly focusing on producing high quality hydrogen. The reactions that occur during the fuel reforming process are exothermic in nature and, thus, generate high temperature products. For example, the temperature of the hydrogen-rich reformate stream exiting a reactor may exceed 1700 degrees Fahrenheit.
Due to the high temperatures involved in the reforming process, the use of fuel reforming systems within gas turbines has been limited. For example, the temperature of the heated reformate stream produced by the reformer may generally exceed the allowable temperature for the material used to form the pipes in the piping system of a gas turbine. As such, to permit the heated reformate stream to be sent directly into the piping system, high temperatures materials would be required for all downstream piping. Such piping, however, would significantly increase material costs for gas turbines. Additionally, the reformer, itself, generally needs to be cooled to prevent overheating and damage to the reformer components. However, additional cooling systems, such as heat exchangers, add unnecessary complexity and expense.
Accordingly, a fuel reformer that provides for cost effective and relatively simple cooling of the heated reformate stream expelled from the reformer, as well as cooling of the reformer itself, would be welcome in the technology.